中文摘要：

采用多目标追踪（MOT）与点探测刺激觉察任务相结合的实验范式，分别通过改变运动与静止非目标数量，考察追踪难度变化对不同类型非目标选择性抑制的影响。实验一通过改变运动非目标数量为4、5、6，发现当运动非目标数量为6时，追踪难度显著增加，静止非目标上的抑制量也显著增加，而运动非目标上的抑制量则不随追踪难度的变化而变化；实验二改变静止非目标数量为4、5、6，同样发现当静止非目标数量为6时，追踪难度显著增加，静止非目标上的抑制量也显著增加，而运动非目标上的抑制量仍不随追踪难度的变化而变化，且当静止非目标数量为6时，静止非目标上的抑制量显著大于运动非目标，出现了反转现象，其原因可能是视野范围内总的对象数量超出了视觉索引容量，被试改变了对静止与运动非目标的抑制策略。综合实验结果表明，静止非目标上的抑制程度随追踪难度的提高而增加；而运动非目标上的抑制程度对追踪难度的变化不敏感，在不同难度水平上保持相对稳定。

英文摘要：

Previous studies have proved that there is a highly localized object - based inhibition on nontargets in Multiple Object Track- ing （MOT） tasks. And the mechanism of selective nontarget inhibition is closely related to the difficulty level of a tracking task. When there is a high demand for a tracking task, more inhibition was obtained to the nontargets that were hard to distinguish from targets with- in the capacity of Visual Index. Using Multiple Object Tracking with Probe Dot Detection tasks, the present study further examined the effects of Multiple Object Tracking difficulty on the mechanism of nontargets inhibition. Two experiments were conducted and both were 3 x 2 within - subject design. The two independent variables were moving nontargets＇ number （ Experiment 1 ： having 4, 5 or 6 moving nontargets while there were always 4 targets and 4 static nontargets） or static nontargets＇ number （ Experiment 2 ： having 4, 5 or 6 static nontargets while there were always 4 targets and 4 moving nontargets） and probe dot locations （ probe dot presented in static or moving nontargets）. Participants in two experiments performed no -tracking task first and then the tracking task. In a no -tracking task, par- ticipants only need to monitor if a probe dot was presented in the objects. In a tracking task, participants must track the targets while monitoring the probe dot. Participants＇ tracking accuracy and probe detection performance on static and moving nontargets were recor- ded. And the degree of inhibition on static and moving nontargets was obtained through percentage of probe detection in a no - tracking task being subtracted from that of tracking task. The results showed that in two experiments, when the number of moving nontargets （Experiment 1 ） or static nontargets （Experiment 2） was 6, the tracking task was significantly more difficult, and the degree of inhibi- tion on static nontargets was significantly larger than that of 4 and 5 moving or static nontargets. However, the inhi